In the prior art, working lamps adopt LEDs as the light source. The heat produced by an LED light source is far lower than that produced by a traditional halogen lamp. It's easier for snowflakes to accumulate on or even freeze the lamp cover of an LED working lamp. As a result, the luminous efficacy of the working lamp can be greatly reduced, and even worse, a user's sight can be seriously blocked.
In order to solve the aforesaid problems, various technical solutions are proposed by those skilled in this art, wherein one of them is to distribute heating wires over the surface of the lamp cover, thereby heating the lamp cover wholly. Its operating principle resembles that of the heating lamp covers of automobiles. This solution has the following shortcomings: first, for the heating wires are relatively thin, the lamp cover cannot be uniformly heated unless a large number of heating wires are distributed on the lamp cover; moreover, the densely distributed heating wires seriously block the light emitted by the light source, resulting in a low luminous efficacy of the working lamp; second, as the strip-shaped heating wires are very thin, and must endure an ultra-high temperature, they can easily fall off after prolonged use. Thus, the functional life of the working lamp can be greatly shortened.